A fundamental change is happening with entertainment—it's going digital. People may now receive digital entertainment on multiple form factors throughout their homes, while at work, while traveling, etc. This presents huge opportunities for content producers and distributors, as did the introduction of radio, movies, television, cable TV, VHS and DVD players. Content producers now have more creative freedom in what they can present, and how it can be presented. Digital distribution models deliver content virtually at any time or any place. The phrases “digital home” and “digital office” are used to represent the hardware and software environments that are being developed to enable diverse digital distribution models in home, office, and other contexts. Each of these contexts includes a network over which content is delivered in the environment.
The Intel® 2003 Networked Media Product Requirements (NMPR) version 1.0 document dated Sep. 12, 2003 describes general principles and structures that may be used to deliver content in digital home, office, and other digital contexts. The Digital Living Network Alliance (DLNA) Home Networked Device Interoperability Guidelines Version: 1.0 dated Jun. 2, 2004 builds on the NMPR (and other such environments) in a cross-industry effort to develop and promote a common industry framework for interoperability of digital home, digital office, etc. devices.
Several basic components of the NMPR and DLNA are described below. The primary focus of the NMPR and DLNA is to enable content interoperability across a network between content sources/hosts and content sinks. Key capabilities include the ability to discover and control content sinks on the network and render content that is discovered dynamically on content sources/hosts. Generally, in the NMPR there are three major high-level logical entities in an environment, Content Sources, Content Hosts, and Content Sinks. Note these logical entities are umbrella terms for devices and/or applications that perform certain roles on the network and each will require a set of differing technologies to implement them. For example, a Content Sink may include an aggregation of multiple devices in order to perform its roles on the network.
Content Sources represent sources of data in the environment, such as digital photos, recorded music, e.g., MP3 files or the like, music delivery services, personal video recordings, video delivery services, etc. Content Sources include applications operating on Content Hosts that provide content and that can be discovered on the network, such as by way of a device discovery protocol such as Universal Plug and Play (UPnP). (Please note that that all marks used herein are the property of their respective owners.) These applications may also provide a user interface (UI) that is remoted (remotely connected) to a remote display device or other Content Sink that allows a user to see, select, play and interact with content. In the DLNA, typical UPnP Content Sources are referred to as Digital Media Servers (DMS).
Content Hosts include platforms that host content provided by Content Sources and provide host stacks that can stream content to Content Sinks. Host stacks may also provide a user interface that is remoted to Content Sinks to allow users to see, select, play and otherwise interact with content from a variety of sources. This content may be a combination of content that is hosted locally on the Content Host and from other network Content Hosts. A user interface may also serve a navigational role by presenting a selection of remoteable user interfaces—much like TV channels—provided by Content Source applications. Host stacks may also support local playback of content located on other Content Hosts.
Content Sinks include devices that play back or render content received over the network from a Content Host. Sinks can also handle user interfaces remoted over the network from a Content Host or Content Source and/or provide a local user interface for the purpose of user control of content selection and playback. In the DLNA, typical UPnP rendering devices or Content Sinks include devices referred to as digital media adapters (DMA) or digital media players (DMP).
While purchasing a device conforming to the NMPR and/or DLNA formats reasonably assures that devices from different developers will interoperate, as a practical matter, providing such interoperability is a non-trivial matter. That is, developing a media product for a digital home typically means your product interacts with other products from different developers using a discovery protocol such as UPnP and a relevant data streaming format, e.g., audio, video, etc. streaming to deliver data from your product to another networked product. It can be difficult to develop, debug and validate one's product. For example, debug and validate streaming functionality of a UPnP-based DMS application, one must send data streams to a DMP (Content Sink). The DMP receives media streams served by the DMS application, decodes the stream, and renders the media stream to an output display device. Unfortunately, if there is a problem, it can be extremely difficult to detect whether an error lies with one's own product, or with another product on the network upon which one's product relies.